JPH0242907Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a compression side damping force adjustment device for a hydraulic shock absorber for a two-wheeled vehicle.

In hydraulic shock absorbers used in motorcycle front walkways, etc., the flow of hydraulic oil that flows into the oil reservoir chamber during compression side operation is controlled by the volume of oil that enters the inner tube, and the compression side damping force can be adjusted according to the driving conditions. There is something like this.

Conventionally, as such a compression side damping force adjusting device, there has been one shown in FIG.

This double-tube hydraulic shock absorber 1 has an outer tube 2
An upper oil chamber A and a lower oil chamber B are defined by a piston section 5 provided at the tip of an inner tube 4 that penetrates into the outer tube 2 with a hollow rod 3 interposed therein. Room C is provided.

An orifice 6 is formed in the lower part of the hollow rod 3 to communicate the oil chamber B and the oil reservoir chamber C, and a compression side damping force adjustment device 9 is housed in parallel thereto.

This compression side damping force adjustment device 9 includes a valve body 8 that passes through the base portion of the outer tube 2 and the oil hole rod 10 and is threadedly engaged with the inner circumferential surface of the hollow rod 3. A cylinder part 11 is formed which opens into the cylinder part 11.
The oil reservoir chamber C and the oil chamber B communicate with each other through a port 12 formed in the valve body 8, an annular oil passage 13, and a port 14 formed in the hollow rod 3.

A substantially cylindrical valve 7 is slidably housed in the cylinder portion 11, and an annular valve seat 15 against which the valve 7 abuts is fixed.

Valve body 8 has valve 7 and valve seat 1
A return spring 16 is interposed to urge the return spring 16 in the direction of contacting the spring 5, and a spring seat 17 that supports one end of the spring 16 is screwed into the spring seat 17. The initial load of the spring 16 can be adjusted by rotating the spring seat 17 from the outside using a screwdriver or the like.

During low-speed operation on the pressure side stroke in which the inner tube 4 enters the outer tube 2, hydraulic oil corresponding to the volume of entry of the inner tube 4 passes through the orifice 6 and is stored in the oil reservoir chamber C.

As the operating speed increases, the pressure in the lower oil chamber B upstream of the orifice 6 increases, and when this increased pressure received by the pressure receiving surface 18 exceeds the set load of the spring 16, the valve 7 opens while compressing it. The valve opening resistance generates a damping force that is primarily proportional to the operating speed.

Incidentally, in the valve 7, a pressure-receiving area is an annular portion defined by the inner diameter of the cylinder portion 11 of the valve body 8 and the inner diameter of the valve seat 15.

However, since the inner diameter of the valve body 8 interposed in the limited space inside the hollow rod 3 is limited, the above-mentioned pressure receiving area cannot be secured sufficiently, and therefore the opening area (maximum value) of the valve 7 is limited. Therefore, the flow rate of the pressure-side hydraulic oil shared by the fixed orifice 6 becomes large, making it difficult to fully exhibit the proportional characteristic of the valve 7 that affects the pressure-side damping force.

An object of the present invention is to provide a compression side damping force adjusting device for a hydraulic shock absorber for a two-wheeled vehicle, which can set a large proportion of the ratio characteristic to the compression side damping force.

Therefore, the present invention provides a valve case that is screwed onto the inner peripheral surface of the hollow rod from the bottom of the shock absorber, and an annular valve seat is attached to the upper end of the valve case. While defining an annular gap that communicates the lower oil chamber B and the oil reservoir chamber C, a substantially cylindrical relief valve that is seated on the upper end surface of the valve seat via a spring can be slid freely on the inner peripheral surface of the hollow rod. to be installed.

Thereby, the flow path area of the pressure-side hydraulic oil flowing through the relief valve can be maximized in the space within the hollow rod 3, and a damping force with stable proportional characteristics can be provided.

Further, by providing a rod that is screwed into the valve case and interposing a return spring between the upper end of this rod and the relief valve, the initial load of the relief valve can be adjusted via the rod.

Further, a plurality of passages are formed in the valve seat in parallel with the annular gap, and an annular check valve is provided that is seated on the lower end surface of the valve seat to supply the lower oil chamber with the extension side hydraulic oil.

Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in FIG. 2, the inner peripheral surface 3 of the hollow rod 3
A valve case 19 is attached to A.

The upper end of this valve case 19 has a reduced diameter portion 20.
An annular oil passage 21 is defined between the outer peripheral surface 20A of the reduced diameter portion 20 and the inner peripheral surface 3A of the hollow rod.

A plurality of ports 45 are formed in the hollow rod 3 to communicate the annular oil passage 21 and the lower oil chamber B.

Step portions 22 and 23 are formed at the upper end of the reduced diameter portion 20, and an annular valve seat 24 is seated on the step portion 23 and fixed by caulking via a washer 25.

A cylinder portion 32 is integrally formed on the inner peripheral surface 3A of the hollow rod, and a substantially cylindrical relief valve 27 is slidably housed in the cylinder portion 32.

The relief valve 27 seated on the upper end surface 26 of the valve seat 24 is connected to the port 45 when the pressure side is operated.
The outflow of hydraulic oil from the lower oil chamber B to the oil reservoir chamber C via the annular oil passage 21 is controlled.

A relief valve 2 is installed on the inner peripheral surface 3A of the hollow rod.
A step portion 46 is formed to prevent the overstroke of No. 7.

A shaft hole 28 is formed in the valve case 19,
A rod 29 is screwed into this shaft hole 28. An annular spring seat 30 is fixed to the upper end of the rod 29 protruding into the oil reservoir chamber C. A conically wound spring 31 is interposed between the spring seat 30 and the relief valve 27.

A cylinder part 34 from which the lower end of the rod 29 projects is formed at the lower end of the valve case 19, and a plug 35 is rotatably housed in the cylinder part 34. A pin 33 is fixed to the lower end of the rod 29, and a notch 36 is formed in the plug 35 to engage with the pin 33 in the rotational direction. Therefore, by rotating this plug 35 using a tool such as a screwdriver, the rod 29 is screwed in the axial direction.
The initial load of the spring 31, that is, the opening pressure of the relief valve 27 can be adjusted.

Note that while a perpendicular hole 39 is formed in the valve case 19, a spring 37 is formed inside the plug 35.
A ball 38 is housed in the hole 39 to prevent the plug 35 from rotating freely. 55 is a packing, and 40 is a retaining ring for preventing the plug 35 from coming off.

The valve seat 24 has a passage 42 that communicates the oil reservoir chamber C and the lower oil chamber B via the annular oil passage 21.
A plurality of annular check valves 43 are formed and seated on the lower surface of the valve seat 24 in the valve case 1.
9, and connect this check valve 43 and the stepped portion 2.
A spring 44 is interposed between the two.

Next, the operation of this valve device will be explained.

When the shock absorber 1 is operated on the pressure side, the pressure in the lower oil chamber B increases due to the entry of the inner tube 4, and this increased pressure acts on the annular pressure receiving surface 47 of the relief valve 27, pushing the relief valve 27 against the return spring 31. Force in the opening direction.

The pressure receiving surface 47 is an axially projected portion of an annular portion sandwiched between the inner diameter of the cylinder portion 32 of the hollow rod 3 and the outer diameter of the valve seat 24.

Therefore, the outer diameter of the pressure-receiving surface 47 can be set to be approximately the same size as the inner diameter of the hollow rod 3, thereby ensuring the largest possible pressure-receiving area for the valve device built into the hollow rod 3.

In this way, the pressure receiving surface 47 of the relief valve 27
Since the area of the buffer 1 can be increased, the passage area at the maximum opening of the relief valve 27, that is, the maximum flow rate can be increased.
Stable proportional damping force characteristics can be obtained from the low-medium speed operating range to the high-speed operating range, and the feeling of the actual vehicle can be greatly improved.

In addition, a stepped portion 46 is formed at the upper end of the cylinder portion 32 to prevent overstroke of the relief valve 27 when a high-speed, large-volume flow flows. Next, the damping force can be increased.

On the other hand, when operating on the extension side, the check valve 43
opens with almost no resistance, and hydraulic oil corresponding to the volume extracted from the inner tube 4 smoothly flows from the oil reservoir chamber C into the lower oil chamber B.

In addition, as shown by the imaginary line in FIG. 2, the hollow rod 3 has a lower oil chamber B in parallel with the relief valve 27.
A fixed orifice 49 may be formed to communicate the oil reservoir chamber C with the oil reservoir chamber C.

In this case, during low-speed operation before the relief valve 27 opens, a damping force that is secondarily proportional to the operating speed is obtained due to the flow path resistance of the fixed orifice 49.

Further, this fixed orifice 49 can compensate for insufficient suction from the check valve 44 during the expansion side operation.

Next, in another embodiment shown in FIG. 3, a valve guide 48 slidably accommodates the relief valve 27.
is provided inside the hollow rod 3.

This valve guide 48 consists of a thin cylindrical part 49 whose inner circumferential surface 49A is in sliding contact with the relief valve outer circumferential surface 27A, and whose outer circumferential surface 49B is fitted into the cylinder inner circumferential surface 3A. An upper bottom portion 52 is formed, which includes a center hole 50 through which the material is inserted, and a plurality of through holes 51 around the center hole 50 .

In this case, the processing accuracy of the surface on which the relief valve 27 comes into sliding contact can be improved, and damage to the relief valve 27 during assembly can be prevented.

In summary, the present invention provides a valve seat at the upper end of the valve case that is screwed onto the inner circumferential surface of a hollow rod, and connects the relief valve's pressure between the outer diameter sliding portion of the valve seat and the outer diameter portion where the relief valve slides. Because it is a flat surface, the relief valve has a large pressure-receiving area and can exhibit stable proportional damping characteristics over a wide operating range from low to high speeds, contributing to improved ride comfort and handling of motorcycles.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a conventional example. Second
The figure is a sectional view of an embodiment of the present invention. FIG. 3 is a sectional view of another embodiment. 1...buffer, 2...outer tube, 3...
Hollow rod, 3A...Hollow rod inner peripheral surface, 19...
...Valve case, 24...Valve seat, 27...
...Relief valve, 29...Rod, 31...Spring, 32...Cylinder part, 46...Step part.

Claims (1)

[Scope of utility model registration request] In a double-tube hydraulic shock absorber in which a hollow rod is interposed inside the outer tube and an oil reservoir chamber is provided inside the hollow rod, a valve case is provided that is screwed into the inner peripheral surface of the hollow rod from the bottom of the shock absorber. A valve seat is provided at the upper end of the valve case, and a cylindrical relief valve is slidably housed along the inner peripheral surface of the hollow rod, and this relief valve is pressed against the valve seat via a spring, A hydraulic shock absorber for a two-wheeled vehicle, characterized in that the pressure receiving surface of the relief valve on which the increased pressure acts during pressure side operation is an annular portion defined by the outer diameter of the valve seat and the inner diameter of the hollow rod.